(1) Field of the Invention
The present invention relates to a post-processing device that is mounted in an image forming apparatus and an image forming system that includes the image forming apparatus and the post-processing device. The present invention relates particularly to an art of improving process for jammed papers in the case where a paper jam occurs during post-processing.
(2) Related Art
According to a general image forming system that includes an image forming apparatus and a post-processing device, one set of a sheet stack that is ejected from the image forming apparatus is conveyed to a post-processing position where post-processing such as stapling is to be performed, and then the sheet stack on which the post-processing has been performed is ejected to an ejection unit that is included in the post-processing device.
In such a post-processing device, a paper jam sometimes occurs during conveyance of the sheet stack. When a paper jam occurs, the system is halted. Accordingly, a user needs to perform a work for restarting post-processing for example by removing the sheet stack in which the paper jam occurs. Such a work increases processing burden imposed on the user, and needs time, and as a result deteriorates productivity of the post-processing.
On the other hand, there is a case where the system does not need to be halted by retrying to convey the sheet stack in which a paper jam occurs depending on the cause for the paper jam. For example, in the case where a paper jam is erroneously detected by a sensor, the system does not need to be halted.
Patent Literature 1 (Japanese Patent Application Publication No. 2010-269908) discloses, as an art of reducing processing burden imposed on a user and preventing deterioration of the productivity of post-processing in the case as above, an art of retrying to convey the sheet stack prior to suspending the post-processing.
However, in the case where conveyance is always retried without suspension of the system, processing for removing jammed papers becomes further complicated and this increases the processing burden imposed on the user. Specifically, while retrial operations of the sheet stack in which a paper jam occurs are performed, the beginning sheet included in a set on which the post-processing is to be subsequently performed is ejected from the image forming apparatus to the post-processing device, and the sheet stack under the retrial contacts the beginning sheet, and as a result another paper jam occurs.
Another paper jam as above is likely to occur in the case where a post-processing device has configuration for example in which one set of a sheet stack on which post-processing is to be subsequently performed is ejected from an image forming apparatus and is stored in a storage tray, and then the sheet stack stored in the storage tray is conveyed to a post-processing position and post processing is performed at the post-processing position.
The present invention was made in view of the above problem, and aims to provide a post-processing device capable of retrying conveyance and preventing increase of a burden of processing for removing jammed papers imposed on a user, and an image forming system including the post-processing device.